Geraldine Bates lost her husband to kidney failure last year. Now, she has fallen behind on her mortgage payments and is terrified that she will lose her home in Jacksonville, Fla.

Ms. Bates, 70, is caught in a foreclosure trap that is ensnaring widows across America: she cannot get help lowering her payments until her name is added to the mortgage note, but the lender says she must be current on payments before that can happen.

“I keep praying,” said Ms. Bates, who is fighting with the bank to stay in the four-bedroom house.

Just as the housing market is recovering, a growing group of homeowners — widows over the age of 50 whose husbands alone were holders of the mortgage — are losing their homes to foreclosure because of a paperwork flaw that keeps them from obtaining loan modifications.